The present application relates generally to a cooling system on a turbomachine; and more particularly to, a system for regulating a cooling fluid within a turbomachine.
In some turbomachines, such as gas turbines, a portion of the air compressed by the compressor is typically diverted from combustion to cool various stationary and rotating components or to purge cavities within a gas turbine. The diverted airflow (hereinafter “cooling fluid”, or the like) consumes a considerable amount of the total airflow compressed by the compressor. The diverted cooling fluid is not combusted, and thus reduces the performance of the gas turbine. Regulating and controlling the cooling fluid can dramatically increase the performance of the turbine.
Typically, the cooling fluid is extracted from the compressor, bypasses the combustion system, and flows through a cooling circuit. The cooling circuit may run adjacent various turbine components including the rotor compressor-turbine joint (hereinafter “marriage joint”), and various wheelspace areas. The cooling circuit is typically integrated with a seal system. Relatively tight clearances may exist between the seal system components and the gas turbine rotor.
The seal system may include labyrinth seals between rotation and stationary components. The typical leakages that may occur through the labyrinth seal clearances are commonly used for cooling or purging areas downstream of the seals. For example, a high-pressure packing seal system (HPPS) may include a labyrinth and brush seal arrangement, wherein the leakage flow past the HPPS cools the downstream components including the wheelspace areas. The effectiveness of the cooling circuit is highly dependent on the performance of the HPPS.
The configuration of the cooling circuit determines whether or not adequate cooling fluid flows to the aforementioned turbine components. The cooling circuit may include a chamber that directs the cooling fluid flow to a specific wheelspace area.
There are a few possible problems with the currently known seal systems. Wear may enlarge the seal system clearances. Seals may wear from a “trip” (an emergency shutdown of the turbomachine). Seals may also wear over time from gas turbine operation. Wearing allows excessive cooling fluid to flow downstream of the seals; reducing the overall efficiency of the gas turbine. The unpredictable nature of the seal system wear occurrence does not allow for a deterministic flow of the cooling fluid through the cooling circuit. Furthermore, the currently known seal systems do not allow for regulating the amount of cooling fluid flowing into the wheelspace areas, in order to compensate for seal system wear. Therefore, the currently known seal systems do not provide a way to increase or decrease the amount of cooling fluid flowing to the wheelspace areas.
For the foregoing reasons, there is a need for a system that allows for regulating the cooling fluid passing into at least one wheelspace area of a gas turbine. The system should ensure adequate cooling while improving the efficiency of the gas turbine. The system should also provide for a deterministic flow through the cooling circuit.